A new sustainable method for processing long industrial hemp fibers has the potential to reduce production times and environmental impact, and deliver more consistent results—marking a key step toward scalability, according to a study by Italian researchers.
The researchers tested a blend of naturally occurring microbes to break down hemp stalks more efficiently during the retting process, according to their paper, published in the journal Industrial Crops and Products, from the Dutch scientific publisher Elsevier.
Cleaner alternative
Retting is the critical phase where fibers are separated from the plant’s woody core (hurd, shivs or shives). Traditionally done with water or harsh chemicals, retting can be slow, resource-intensive, and environmentally damaging.
The approach used for the study selected groups of microbes to accelerate the breakdown process. It avoids synthetic chemicals and operates with lower water and energy requirements—making it a cleaner, more sustainable alternative.
“As researchers refine these microbial systems, the opportunity to create consistent, lower-impact alternatives to traditional retting becomes increasingly viable for industrial-scale applications,” said Joseph Carringer of the U.S. consultancy Canna Markets Group.
Stronger, faster fibers
In hemp processing, the distinction between long and short fibers is critical to understanding both market value and end-use potential. Long fibers, which can extend over a meter in length, are carefully extracted from the outer layer of the stalk through retting and gentle mechanical separation. These fibers are prized for their strength, durability, and consistency, making them essential in high-value applications like textiles, biocomposites, insulation, and technical materials. Producing long fiber requires greater precision in harvesting and processing but commands a premium in the marketplace.
In contrast, short fibers—often referred to as tow or fiber fines—are broken, irregular fragments typically less than 10 centimeters long. These result from faster, more aggressive decortication or are derived as byproducts of fiber processing. While they’re less valuable per ton, short fibers serve important roles in nonwoven materials, injection-molded plastics, animal bedding, and mulch. Facilities focused on long fiber must invest in more sophisticated retting and fiber-handling systems, but the payoff is access to more demanding—and lucrative—industrial supply chains.
In the study, fiber separation was achieved in just 7 to 14 days—about half the time of conventional water retting—without reducing yield or compromising quality. The resulting fibers were lighter in color and more uniform in composition, making them better suited for high-value markets.
Commercial upside
The researchers also found that the microbial mix could be simplified without losing performance. Carringer said such biological retting offers “a promising path toward scalable, environmentally responsible hemp fiber processing,”
The study noted that factors such as temperature, water quality, and hemp variety can influence results—important considerations for commercial deployment.
The research was carried out by a team at the University of Naples Federico II, Italy, including Ilaria Zezza, Silvia Pascale, Massimo Fagnano, Loredana Bressan, Alessandro Schiavo, Aniello Anastasio, and Mariarosaria Aleandri.